The present invention relates to the automatic extraction of defective weft threads or picks during weaving on a shuttleless loom, for example, an air jet loom. More specifically, the invention relates to the freeing of a defective weft thread from the fabric in order to facilitate its extraction.
Air jet looms conventionally utilize weft sensors that check if the weft thread that has been inserted in the warp is defective and, if a defective pick is sensed, include a system for stopping the loom. Usually, a mispick is manifested by a weft thread folded up on itself among the warp threads. The extraction of the defective pick usually is accomplished by the loom operator who, with the warp open, frees up the defective weft thread that has usually been beaten by the reed (sley) into the fell and cut at its inserted side, and extracts the defective weft by hand. Various devices have been proposed for accomplishing such extraction automatically. Usually, other devices include a means which is external of the fabric being woven and which only acts when the weft sensors have sensed and indicated a mispick.
For example, in French Patent No. 83,19156, the weft remover is placed at the insertion side of the loom and, in the event of a mispick, reciprocates in the direction of the weft through the warp, thereby moving the defective weft as it advances. The defective weft is only sensed by the device after the weft has been beaten into the fell of the fabric. According to European Patent Specification No. 83 10 7125.3, the defective weft remover is placed on the front part of the loom and above the fabric being woven. In this case, in the event of a defective pick, the remover drops and is introduced between the defective weft and the fabric in order to free the defective weft. Again, the introduction of the freeing means is carried out only after the beating up of the defective weft thread.
Obviously, the introduction of a freeing means between two weft threads beaten against one another is very difficult, if not impossible.